The fourth episode starts off with the two riding through Santa Cruz, Argentina. The plan is to cross over into Chile and then going up into the Andes. Ewan and Charley head through Argentina’s red rock landscape while a member of their team copes with altitude sickness. The duo are well and truly underway and the first signs of all are well is how well the Harleys hold up in challenging conditions. The roads alternate between unforgiving and pleasant and these e-bikes push through effortlessly. As they ride through Chilean Andes, the audience is shown a picturesque view of the beauty of the countryside, an experience which Boorman calls 'magical.'

Dr Nigel Spivey explores how art influences life by tracing the development of the image from cave paintings to our modern obsession with images. Dr. Spivey begins his investigation by travelling to the Cave of Altamira near the town of Santillana del Mar in Cantabria, Spain, where in 1879 a young girls exclamation of 'Papa, look, oxen!' to her father, local amateur archaeologist Marcelino Sanz de Sautuola, is explained to have meant that Maria had just become the first modern human to set eyes on the first gallery of prehistoric paintings ever to be discovered.

Experts suspect that the dinosaurs were wiped out after a city-sized asteroid smashed into the Gulf of Mexico causing a huge crater. But until now, they haven't had any proof. In a world first, evolutionary biologist Ben Garrod joins a multi-million pound drilling expedition into the exact spot the asteroid hit to get hard evidence of the link. The team overcomes huge obstacles as it attempts to drill 1,500 metres beneath sea level to pull up rock from the Chicxulub crater. Meanwhile, paleopathologist Professor Alice Roberts travels the globe meeting top scientists and gaining exclusive access to a mass fossil graveyard in New Jersey - believed to date from the same time the asteroid hit. Alice also treks by horseback across the remote plains of Patagonia, to see if the effects of the asteroid impact could have wiped out dinosaurs across the world - almost immediately.

Laurent Ballesta has yet again challenged himself to a new world record: spend 28 days at a depth of 100 meters to reveal the luxuriant and unknown depths of the Mediterranean.
Because people have been travelling there for thousands of years, this sea is be­lieved to be without secrets. And yet, far below its surface, lie vast unexplored territories, luxurious gardens worthy of the finest tro­pical coral reefs. These natural wonders are inaccessible to the traditional diver, in a twilight zone, between 60 and 120 m, where there’s less than 1% of sunlight. If diving at such depths is always a challenge, staying there is a fan­tasy, a utopia that becomes reality in 'The Deep Med'.

Many consider it the greatest team ever assembled, in any sport. Yet even that description fails to give it proper credit for its impact. The original the Dream Team, the first U.S. Olympic team to include NBA stars was a phenomenon on and off the court. It mattered not that it dominated the Olympic competition. It won the gold medal at the 1992 Olympics in Barcelona, beating its eight opponents by an average of 44 points. What was important was that the Dream Team, gave fans a glimpse of basketball at its finest, and an entire world responded. The film is the definitive documentary of the historic 1992 USA Basketball team, featuring recent interviews with all 12 members, including Michael Jordan, Magic Johnson, Larry Bird, and Charles Barkley. Includes rare footage from USA Basketball's film library, and the untold story behind what has become part of basketball legend. Since 1992, basketball has exploded in popularity around the globe, rising to a place where it truly challenges soccer's status as the world's most popular sport. Much of that is due to the impact of the Dream Team, which attracted fans and followers wherever it went. "It was," said Coach Chuck Daly, "like Elvis and the Beatles put together. Traveling with the Dream Team was like traveling with 12 rock stars. That's all I can compare it to." And what a band it was. Start with three of the game's all-time greats: Michael Jordan, Magic Johnson and Larry Bird. Add the irrepressible Charles Barkley for a little spice, as well as seven more NBA All-Stars: centers David Robinson and Patrick Ewing, power forward Karl Malone, swingmen Scottie Pippen, Chris Mullin and Clyde Drexler and point guard John Stockton. Complete the roster with Christian Laettner, the best college player of 1991-92 and a future NBA All-Star. Opponents didn't have a chance, but they didn't care.

Al-Khalili travels to northern Syria to discover how, a thousand years ago, the great astronomer and mathematician Al-Biruni estimated the size of the earth to within a few hundred miles of the correct figure. He discovers how medieval Islamic scholars helped turn the magical and occult practice of alchemy into modern chemistry. In Cairo, he tells the story of the extraordinary physicist Ibn al-Haytham, who helped establish the modern science of optics and proved one of the most fundamental principles in physics - that light travels in straight lines. Prof Al-Khalili argues that these scholars are among the first people to insist that all scientific theories are backed up by careful experimental observation, bringing a rigour to science that didn't really exist before.